MCP server: EU registers and supplement-law knowledge inside your AI assistant

How do you connect an AI assistant (Claude, ChatGPT, Cursor) to verified EU/Polish food-law data instead of relying on the model’s memory? Add one address: https://mcp.supplemental.pl/mcp. The assistant then queries the official register or a knowledge-base article and cites the source in its answer.

Tomasz Krawczyk · supplemental.pl · 28 October 2026

What the supplemental.pl MCP server is

MCP (Model Context Protocol) is an open standard through which an AI assistant calls external “tools” and receives an answer from the actual source instead of reconstructing it from memory. For a regulatory team, this is the difference between “the model recalls that vitamin D has some claims” and “the model showed the EU Register entry with its conditions of use and legal act”.

Our server is public, read-only, with no sign-in and no key. Address: https://mcp.supplemental.pl/mcp. Transport: Streamable HTTP, stateless (MCP 2026-07-28; older clients connect via initialize with versions 2025-11-25, 2025-06-18 and 2025-03-26). Every answer includes a link to a supplemental.pl page, the legal source (act or register) and a notice that it is not legal advice. Answers contain no prices.

• Official MCP Registry entry: pl.supplemental/foodlaw
• Server card: mcp.supplemental.pl/.well-known/mcp/server-card.json
• Data status (download date, record counts): mcp.supplemental.pl/health
• Limits: 60 requests per minute per IP address; Nutrimetr calculator — 20 calculations per user per day; C.L.A.I.M.S. has its own daily limit.
• Privacy: the server only counts aggregated tool calls (day, tool, MCP client name), with no IP addresses and no query content. The IP address is used only for the live rate limit; for the C.L.A.I.M.S. and Nutrimetr tools, the query and the IP address are passed to those services, which answer it and apply their daily limit. Details: privacy policy.

Eight tools in plain language

Example questions

Each question below was run through the server on 28 October 2026. Statuses in Commission registers can change, which is why every answer links to the source entry.

Search the Novel Food Catalogue by the full Latin or chemical name. Abbreviations (such as “NMN”) may not be indexed, and the absence of an entry does not mean that a product is not novel.

How to connect the server

Menu paths checked against the vendors’ documentation on 28 October 2026. Interfaces change often; if anything differs, the linked documentation prevails.

Claude (claude.ai, Claude Desktop, Cowork)

Individual plans (Anthropic documents this path for Pro and Max; the Free plan allows one custom connector):

1. Customize → Connectors.
2. + Add → Add custom connector.
3. Name, e.g. supplemental.pl; server URL: https://mcp.supplemental.pl/mcp → Continue. Review the detected authentication settings → Continue.
4. Under Authentication, choose No sign in (the server needs no sign-in) → Add.
5. In a chat: the + button at the lower left → Connectors → switch the connector on and ask your question.

Team and Enterprise: an Owner or Primary Owner (on Enterprise also anyone with a custom role that includes “Manage access to Libraries”) first adds the connector for the organisation: Organization settings → Connectors → Add → hover over Custom → Web, then as above. Members go to Customize → Connectors and click Connect next to the connector.

The connection to the server is made from Anthropic’s cloud, not from the user’s computer, so the server has to be publicly reachable (ours is). Connectors added in claude.ai are automatically available in Claude Code when you are logged in with your claude.ai account (list them with /mcp).

Sources: Claude Help Center — Get started with custom connectors using remote MCP; Claude Code — MCP.

claude mcp add --transport http supplemental https://mcp.supplemental.pl/mcp

ChatGPT

1. Go to Plugins.
2. Select the + button → Add custom MCP server.
3. Enter a name (optionally a description); under Connection, paste https://mcp.supplemental.pl/mcp.
4. Authentication: none (the server is public).
5. Tick I understand and want to continue at the risk warning → Create as a plugin → review the discovered tools.
6. Install the plugin, start a new conversation, type @ and select the plugin.

Availability depends on the plan. According to OpenAI, full support for custom MCP servers is available on Business and Enterprise/Edu, on the web only (not in the mobile app). On Business, an admin or owner creates and publishes the plugin; on Enterprise/Edu, an admin can grant this permission to selected members via RBAC. Pro users can connect MCP servers with read/fetch permissions — which is enough, because our server is read-only. The older path (Workspace settings or user settings → Apps → Create) is described in the documentation as a “legacy” configuration.

Testing without ChatGPT: in the API Playground, choose Tools → Add → MCP Server and enter the server address.

Sources: OpenAI Help Center — Connecting custom MCP servers in ChatGPT; OpenAI Developers — Connect and test your plugin.

Cursor

Create ~/.cursor/mcp.json (global, for all projects) or .cursor/mcp.json in the project folder. Both files are merged; if the same server name appears in both, the project configuration takes priority. Save the file and restart Cursor.

{
  "mcpServers": {
    "supplemental": {
      "url": "https://mcp.supplemental.pl/mcp"
    }
  }
}

A remote server in Cursor needs only the url field; no headers are required because the server needs no key. You can switch the server on or off later under Customize in the sidebar.

Sources: Cursor Docs — Model Context Protocol; Cursor Help — MCP.

curl -s https://mcp.supplemental.pl/mcp -H 'content-type: application/json' \
  -H 'MCP-Protocol-Version: 2026-07-28' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list","params":{"_meta":{"io.modelcontextprotocol/protocolVersion":"2026-07-28","io.modelcontextprotocol/clientCapabilities":{},"io.modelcontextprotocol/clientInfo":{"name":"my-app","version":"1.0"}}}}'

Data sources and licences

• EU Register of nutrition and health claims — European Commission data (DG SANTE), refreshed on the server weekly. Reused under CC BY 4.0 in line with the Commission’s reuse policy (Commission Decision of 12 December 2011, 2011/833/EU). Attribution: “© European Union, data: EU Register of nutrition and health claims”.
• EU Novel Food Catalogue — EC data (DG SANTE), CC BY 4.0, refreshed weekly. The Commission describes the catalogue as non-binding; the catalogue page states: Please note that the new Novel Food status Catalogue is a non-binding tool that lists products of animal and plant origin, algal and fungal species, cultures of micro-organisms and other substances subject to the Novel Food Regulation, based on information provided by the EU Member States. This should be read in conjunction with the Union list of novel foods and It is a non-exhaustive list and serves as orientation on whether a product will need an authorisation under the Novel Food Regulation. What is binding is Regulation (EU) 2015/2283 and the Union list (Implementing Regulation (EU) 2017/2470).
• Legal acts: Regulation (EC) No 1924/2006, Regulation (EU) No 432/2012, Regulation (EU) 2015/2283, Implementing Regulation (EU) 2017/2470 (EUR-Lex); the Polish Act on Food and Nutrition Safety (ISAP).
• C.L.A.I.M.S. (FOODLAW.ai) and Nutrimetr — proprietary tools. Nutrimetr calculates deterministically, without AI.
• supplemental.pl articles — own content © supplemental.pl; the server returns an excerpt (up to 6,000 characters) with a link to the full text.

Disclaimer

Frequently asked questions